Spain continues to grapple with the effects of severe floods that have swept through the eastern and southern regions in recent weeks. Due to ongoing climate warming, such heavy, torrential rains causing flash floods may become an increasingly frequent problem in Europe – hydrologists warn. They emphasize that cities will particularly feel the impact. The key role here is not only climate change adaptation, but also preparing residents for possible dangers.
“Floods in Spain are occurring more frequently and the reason for this is quite simple, it’s climate change. The temperature of the water in the Mediterranean is rising – this year it was record-breaking, which excited the media. This high temperature when met with cold air or a cold stream results in extreme moisture absorption leading to phenomena we saw in Spain,” says Professor Paweł Rowiński, a hydrologist and chairman of the Water Science and Water Management Committee at the Presidium of the Polish Academy of Sciences. “Climate change means that the temperature is rising and more water vapour is being absorbed by the atmosphere. Each additional 1°C results in approximately 7% more humidity and this causes the heavy rainfall. If such heavy rainfall occurs after a dry period, flash floods occur.”
At the end of October, intense downpours caused river flooding and flash floods in many Spanish provinces, including Valencia, Castile-La Mancha, and Andalusia. Over 220 people died, dozens are still missing. The disaster caused severe destruction and material losses – transportation was paralyzed, streets turned into raging rivers, property and dozens of cars were swept away, buildings and infrastructure got destroyed, and tens of thousands of households were cut off from drinking water and electricity.
Just two weeks later, parts of Spain were again under water. Intense rainfall occurred again in provinces such as Valencia and Alicante in the east of the country, with severe damage also reported in Catalonia and Majorca. The capital, Madrid, has allocated over 10 billion euros to deal with the aftermath. Spanish media reports that these flash floods are the worst natural disaster the country has seen in decades.
“Such phenomena themselves have occurred in the past, but they are becoming increasingly intense. Rain clouds contain much more moisture and recent downpours in Valencia were indeed extreme. We now have a repeat of history and powerful downpours are occurring not just in Spain, but also in Italy, where Sicily is also struggling with a major flood,” says Professor Rowiński.
The violent storms and flash floods in Spain were the result of an atmospheric phenomenon known as DANA (depresion aislada en niveles altos), which also occurs in the whole Mediterranean basin. This is caused when cold air over the Mediterranean meets warm and humid air, leading to extreme weather events such as violent storms, tornadoes and floods.
“The recent flood we had in Poland and several other European countries was also caused by a Genoese current from the Mediterranean, so the cause was quite similar. As you can see, a hot Mediterranean Sea can cause devastation in almost any part of Europe. However, floods can also occur as a result of other factors. In Poland, for example, they can be caused by thawing ice in winter, so there are many causes of flooding. And unfortunately, there will be a lot more,” the hydrologist predicts.
As he emphasizes, it is important to prepare adequately for such scenarios. This includes preparing crisis scenarios and early warning system for residents about threats.
“The Spanish meteorological services were predicting the rainfall amounts two or three days in advance, which actually checked out. So, there were signals that these would be extreme rainfall, but this is a matter of imagining what the consequences may be and preparing for the situation. And there, people were trapped in cars that were sinking. In Sicily, the situation is repeating,” says Professor Rowiński. “One of the most important elements of preparation is crisis response, i.e., warning residents and introducing the correct procedures. They need to know what to do when there’s severe rainfall and that they shouldn’t run away in their car. This happened in Spain and that’s why there were so many dramas. There is a vast space for improvement in crisis response in almost every country in Europe.”
The expert stresses that this applies particularly to cities, as they are especially vulnerable to the extreme effects of climate change. Therefore, adaptation to new conditions plays a crucial role in their case.
“Some of the cities are already doing this, but not on a large enough scale. This is not just about flooding, Spanish cities are mainly exposed to droughts, which are a problem there all year round. And after a long dry period, when the ground is baked and hard, if such heavy rainfall comes, the ground cannot absorb the water and we have powerful floods. Now, cities need to be prepared for these extreme phenomena to occur more frequently, they need to have a way to adapt to climate changes,” adds the expert.
As the European Parliament for the European Environment Agency reports, 2023 was the warmest year in over 100,000 years. This leads to record heatwaves and wildfires. Last year, fires consumed 500,000 hectares, especially in Greece, Spain, Portugal, and Italy. Over the last 30 years, floods have affected 5.5 million people in the EU, caused the death of 3,000 people and more than 170 billion euros in economic losses.
